Question

Hey !!

What are Infra - Red rays ?

Proper Explanation Needed.

No Lazy answers.

Answer 1

Hi,

Here is your answer,

INFRA - RED RAYS

Infra-Red Rays were discovered by ''HERSCHELL''. Infra-red Rays are hear radiation and therefore all hot bodies are he sources of infra red rays. About 60% of the solar radiation is infra red in Nature.

Infrared waves, with frequencies lower than those of visible light, vibrate not only the electrons, but entire atoms or molecules of a substance. This vibration increases the internal energy and consequently, the temperature of the substance. Infrared waves are sometimes referred to as heat waves

FEW SOURCES TO PRODUCE INFRA RED RAYS

• Nernst Lamp :- The filament of Nernst Lamp is made from the mixture of zirconium, thorium and cesium. When current is passed through such a filament, then at a temperature of about 1200 K, infra red rays are emitted.
• Globar :- It is basically a rod of silicon carbide, which when heated to a temperature of about 900 K by passing current, produces infra red rays.
• LASER :- It is used to produce monochromatic infra red rays. For example:- He - Ne LASER provides infra red rays of wavelength 0.69 × 10⁻⁶ m , 1.19 × 10⁻⁶ m and 3.39 × 10⁻⁶ m. CO₂ LASER provides infra-red rays of wavelength 10.6 × 10⁻⁶ m.

• To defect infra red rays, thermocouples, thermopiles,bolometers, photo conducting cells are used.

Hope it helps you !

Answer 2

Infra-red ( IR) radiation is one part of the electromagnetic spectrum, just like gamma rays, X-rays, UV, visible light, microwaves & radio waves. It occupies the region between the extreme red end of the visible spectrum and microwaves, wavelengths of 700nm - 1mm. ( alternative measures are available, frequency, eV and 'reciprocal centimetres' [ cm e-1 ] depending upon the field in which you are working. Conversion charts are readily available ). The region is further subdivided into Near Infrared, Mid IR, Longwavelength IR & far IR, depending upon application.

Any body above absolute zero will emit IR radiation, although hotter bodies emit more. The wavelength(s) also varies with temperature. It is what we experience as heat if you hold your hand near to a hot object, and also the warmth we feel from the Sun.

Just like any other form of electromagnetic radiation, IR travels in straight lines, and can be focussed & manipulated just like light rays. For practical purposes, due to the absorbtion of IR by SiO2 molecules in glass, focussing is carried out using 1st surface mirrors, rather than lenses. [ Think Newtonian reflecting telescope ].

Applications of IR are many & varied. Shorter wavelengths can be used for communication ( TV remote control ) Mid IR can be used for chemical analysis ( which is the field that I have most experience with ), because the energy of the photons is similar to the vibrational energies of chemical bonds within the molecule, and can be used to generate characteristic 'fingerprint spectra' of (typically) organic molecules. Longer wavelengths can be used for thermal imaging ( wildlife & Police cameras ), detection of hot spots in machines, weapons guidance, remote temperature measurement. It can also be used in heating, anything from small localised areas to saunas. Astronomy uses IR telescopes to see into certain parts of the Galaxy, because the longer wavelengths are not blocked by intervening dust particles, so can see into places that are 'dark' to visible light telescopes.